Beam-compass



-(1I0 Model.)

.YJ. STRAGHAN.

BEAM COMPASS. No. 374,639.. I Patented Dec@ 13, 1887.

N. PETERS. Phowuma m n r. Wishi n nnnnn c.

v To all whom it. may concern:

" UNITED STATES PATENT OFFICE.

JOSEPH STRAGH AN, OF BROOKLYN, NEW YORK.-

BEAM-COMPASS.

, SPECIFICATION forming part of Letters Patent No. 374,639, dated December 13, 1887.

Application filed September], 1887. Serial No. 5148.437. (No molel.)

Be it known that I, JOSEPH STRAOHAN, a citizen of theUnited States, residing in Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Beam-Compasses, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, which form part of this specification.

The invention relates to that class of compasses in which the holder for supporting the marking instrument or the central pivotal arm, or both, is a separate piece,and is adapted to move on the radial arm of the compass.

The objects of my invention are to provide a holder which'is simple in construction and inexpensive, which can be applied to any.

straight edge, which is capable of slow motion, wherebyit can be moved over minute distances with accuracy and ease, and which is adapted to support any size or form of marking-instrument or central pivotal arm.

My invention consists in the devices and combinations of devices, hereinafter described and claimed as such.

In the accompanying drawings, Figure 1 is a side view, Fig. 2 is a plan view from below, and Fig. 3 is an end view, of my improved beam-compass.

A is the arm of the compass, which is made in any usual Way, with a straight edge on the under side, and is mounted on a central pivotal arm, B, as shown in Fig. 1. The straight edge might be made on the top of the arm A, or even on the side; but my invention can be most conveniently applied when the straight edge is below.

a is the holder of my compass, and is preferably made in the form shown, though it could be greatly modified in form without departing from my invention. It is adapted to receive the arm A and to move on that arm.

I) is a set-screw working in theholder a,and bearing against the arm A through and by means of the clamp-plate 1. Attached to the clamp-plate l are two guide-bolts, m m, which slide in holes in the holder a and serve to hold the plate Z in proper position. VVhen the holder is to be moved on the arm A, the setscrew b is unscrewed a little and the plate Z drawn back. When the holder has been moved into its proper place, the set-screw bis screwed up, and the holder is thus firmly fixed in its place.

c c are spring-pieces, made of any suitable elastic material. They are pivoted to the side of the holder, which moves on the straight edge of the compas's-arm. These spring-pieces are curved or bent, preferably in the .manner shown, so that when they are depressed by the hand their free ends will bear against the straight edge of the compass arm. Instead of being'evenly curved, as shown, the spring piece could be bent somewhere between its extremities. I prefer to make these springpieces 0 of such a length that when they are not in use they can be turned under the side or bottom of the holder, so as to be entirely protected, as shown in dotted lines in Figs. 1 and 2. In Fig. 1 two holders are shown, one supporting the marking-instrument, the other su'pportingthe central pivotal arm or needle. They are similar in construction, the opposite sides being exhibited in the said figure. A complete beam-compass would preferably consist of two such devices.

dis a lever for gripping and holding the marking-instrument. It is pivoted to an ear or ears projecting from the side of the holder at. A screw, e, works in a hole in one end of this lever, the end of this screw bearing or pressing against the side of the holder a.

f is a slight shoulder raised on the side of I against the marking-instrument and clamp it against the sides of the holder. By this means any form or size of marking-instrument can be supported in the holder.

When it is desired to move the holder a in either direction on the compass-arm, the setscrew b is loosened slightly, and the springpiece on the side away from the direction in which the holder is to be moved is depressed, and the free end of this spring-piece bears against the straight edge of the compass-arm, and as the spring-piece is straightened under the pressure the holder is moved slowly and evenly along the compass-arm. By means of these spring-pieces the holder is made capable of the most delicate adjustment, and this adjustment is effectedwith the greatest ease.

In place of using two spring-pieces, c a, only one need be employed, if desired, though I prefer the form shown. If only one springpiece be used, the operation would be the same in one direction. In moving the holder in a direction toward the single spring-piece it would have to be moved by the hand some distance beyond the desired point and then brought back to that point by pressing the spring-piece.

Some parts of my invention can be used without the others. I do not therefore confine my claims to the combination of all-the features or parts shown.

What I claim as new, and desire to secure by Letters Patent, is-

1. A holder for a beam-compass, consisting of a portion adapted to move on the straight edge and be fastened in any position and hold theinstrument, and a spring-piece havingone end fastened to the said portion and the free end adapted to bear against the straight edge, whereby, when the spring-piece is depressed, theholder will be moved on the straight edge.

2. A holder for a beam-compass, substantially as shown and described, consisting of a portion adapted to move on the straight edge and be fastened in any position and hold the instrument, and two spring-pieces fastened to portion adapted to move on the straight edge and be fastened in any position and hold the instrument, and two spring-pieces pivoted to the said port-ion on opposite sides, their free ends being adapted to bear against the straight edge, whereby, when not in use, the springpieces can be turned under the holder, and when the spring-pieces are extended the holder can be moved in either direction by depressing the proper springpiece.

4. A holder for a beam-compass, substantially as shown and described, consisting of a portion adapted to move on the straight'edge and be fastened in any position, a spring-piece having one end fastened to the said portion, its free end being adapted tobear against the straight edge, and a lever pivotally mounted near its middle point on the said portion of the holder, and a screw working in oneend of the lever and bearing against the side of the holder.

5. A holder for a beam-compass, substantially as shown and described, consisting of a portion adapted to move on the straight edge, two spring-pieces fastened to the said portion, their free ends being adapted to' bear against the straight edge on opposite sides of the holder, a lever pivotally mounted near its middle point on the said portion of the holder, and a screw working in oneend of the lever and bearing against the side of the holder.

JOSEPH STRACHAN.

Witnesses:

ROBERT N. KENYoN, EDWIN SEGER. 

